(a) Technical Field
The present invention relates to an apparatus for regenerating a carbon dioxide absorption solution. More particularly, it relates to a carbon dioxide absorption solution regenerating apparatus capable of regenerating an absorption solution which absorbs carbon dioxide (hereinafter, CO2) contained in a combustion exhaust gas emitted during a combustion process of a vehicle.
(b) Background Art
Representatives from all over the world, perceiving the seriousness of global warming, gathered at Rio de Janeiro in Brazil in 1992 to sign up for the Framework Convention on Climate Change, the objective of which was to prepare a regulation plan for a period of time through 2000 whereby emissions of CO2 which cause global warming would be reduced to below the 1990 level. The Convention was detailed in the enforcement plan according to the 1997 Kyoto Protocol, and the countries directly involved finally agreed to the enforcement plan of the Kyoto Protocol at the 7th general meeting in November of 2001. Accordingly, the leading countries (countries in Annex 1 of the Kyoto Protocol) accepted and have been carrying out a compulsory greenhouse gas emission reduction plan. According to the results discussed by the countries directly involved on Dec. 13, 2007, Korea is expected to voluntarily carry out the compulsory greenhouse gas emission reduction plan after 2012. Korea was ranked at the top among the countries having the fastest increasing rate in its greenhouse gas emissions between 1990 and 2004, and still has the fastest increasing rate in its greenhouse gas emissions. Considering that 25% of the total amount of emitted greenhouse gas is emitted during a manufacturing process, it is urgent to prepare a greenhouse gas emission reduction plan to address that.
The methods for reducing the amount of CO2 emission which occupies most of the amount of greenhouse gas emissions may generally be divided into the reduction of energy consumption, CO2 recovery/storage, use of alternative energy, etc. Of these, the CO2 recovery/storage method is under active development, particularly because it has the advantages of having little effect on industrial activities while enabling reuse of the recovered CO2.
Among CO2 absorption techniques, a chemical absorption method has been drawing much attention particularly because it is highly efficient in removing CO2 and because it also enables processing of a mass flow of exhaust gas even at a relatively low CO2 concentration of about 8 to 15 percent, which is the CO2 contained in combustion exhaust gases emitted in most of manufacturing processes. Thus, chemical absorption provides advantages in terms of cost effectiveness and process applicability over the conventional recovering techniques such as adsorption methods and membrane separation methods.
To perform such a chemical absorption method, it has been very common to use as a CO2 absorption solution regenerating apparatus a conventional apparatus. Generally the conventional apparatus in one in which an absorption solution that absorbs CO2 from an absorption column is heated to a predetermined temperature so that CO2 can be separated from the absorption solution, thereby regenerating the absorption solution, and at the same time, separating and recovering CO2.
Korean Patent No. 0962871 provides an example of a CO2 absorption solution regenerating apparatus that improves upon the conventional apparatus. In particular, the improved apparatus is configured to preheat an absorption solution with heat generated while compressing CO2 at high pressure. FIG. 1 is a schematic configuration view showing an apparatus for regenerating a CO2 absorption solution according to an illustrative embodiment of Korean Patent No. 0962871.
Such a CO2 absorption solution regenerating apparatus, as shown in FIG. 1, is configured to perform preheating an absorption solution additionally by using waste heat which is created when heat is generated from a compressor during CO2 compression and when an absorption solution condensed in a separation drum of a regeneration column is refluxed to the regeneration column, thereby improving thermal efficiency in an upper portion of the regeneration column.
In particular, in the CO2 absorption solution regenerating apparatus as shown in FIG. 1, an absorption solution supplied to the absorption column at atmospheric pressure makes contact with a combustion exhaust gas containing CO2 emitted during a manufacturing process to thereby absorb CO2. Then, the absorption solution of the thus absorbed CO2 is stored in a storage tank 10 (e.g., at around 90° C.) and is again transported to a CO2 compressor 11 to be preheated.
The absorption solution that is thus transported recovers (exchanges) heat generated when CO2 is compressed in the CO2 compressor 11 using a heat exchanger mounted in the CO2 compressor (e.g., at around 90° C.), and is thereby transported to a high temperature absorption solution flow rate control tank 12.
The absorption solution transported to the high temperature absorption solution flow rate control tank 12 is stored therein over a predetermined time, and provides flow rate control, and thereafter flows into a first heat exchanger 13. The absorption solution that flows into the first heat exchanger 13 exchanges heat therein with a regenerated absorption solution that is emitted at a relatively high temperature (e.g., around 100° C.), as compared to the absorption solution, through an absorption solution heater 17 at a lower position of the regeneration column 15. As a result, the absorption solution is thereby increased in temperature (e.g., to around 97° C.) and flows into an upper portion of the regeneration column 15.
As the absorption solution flows into the upper portion of the regeneration column 15 and passes through a storage station in the regeneration column 15 to flow into a lower portion thereof, the absorption solution is further heated so that CO2 is separated from the absorption solution, and, finally, is regenerated. Here, the absorption solution, which was heated and vaporized, ascends toward an upper portion of the regeneration column 15, is discharged together with the separated CO2, and is then compressed by the CO2 compressor 11 to be stored in the storage tank 20 via a cooler.
As described above and as shown in FIG. 1, the separated CO2 and the vaporized absorption solution as a CO2 state at a high concentration of more than 99% are cooled in the cooler 16 for transporting to the separation drum 18, where they are then condensed in the separation drum 18, thereby decreasing their temperature (e.g., to around 6° C.). The absorption solution condensed in the separation drum 18 exchanges heat with the absorption solution (e.g., at around 92° C.) that was regenerated during flowing through the second heat exchanger 14 to the first heat exchanger 13. The absorption solution thereby is increased in its temperature (e.g., to around 82° C.) and is refluxed into an upper portion of the regeneration column 15. The apparatus is further configured so that the absorption solution regenerated in the second heat exchanger 14 is transported to an absorption column.
However, even when such a conventional CO2 absorption solution regenerating apparatus is used, the regeneration of an absorption solution still requires a great amount of energy. Accordingly, there has been a long awaited need for the development of a system for regenerating a CO2 absorption solution which is capable of reducing costs in such processes.
Further, such a conventional CO2 absorption solution regenerating apparatus is configured to have multi-stepped compressors for compressing CO2 at a high pressure. However, there has been a problem in that absorption solutions vary in temperature and in the amount of heat exchange with such multi-stepped compressors.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.